Recent Developments in Radiotherapy

It is estimated that 470,000 patients receive radiotherapy each year in the United States. 1 As many as half of patients with cancer will receive radiotherapy. 2 Improvements in diagnosis, therapy, and supportive care have led to increasing numbers of cancer survivors. 3 In response, the emphasis of radiation oncology has expanded beyond cure to include reducing side effects, particularly late effects, which may substantially affect a patient's quality of life. Radiotherapy is used to treat benign and malignant diseases and can be used alone or in combination with chemotherapy, surgery, or both. For primary tumors or metastatic deposits, palliative radiotherapy is often used to reduce pain or mass effect (due to spinal cord compression, brain metastases, or airway obstruction). Therapeutic radiation can be delivered from outside the patient, known as external-beam radiation therapy, or EBRT (see the Glossary in the Supplementary Appendix, available with the full text of this article at NEJM.org), by implanting radioactive sources in cavities or tissues (brachytherapy), or through systemic administration of radiopharmaceutical agents. Multiple technological and biologic advances have fundamentally altered the field of radiation oncology since it was last reviewed in the Journal.(4)